Summer's first big respite -- the Memorial Day holiday weekend--promises that rarest of combinations for Washington-area celebrants: mostly sunny days with cool temperatures and relatively construction-free highways to escape town.

First, the weather report: National Weather Service forecaster Walter Green promises daytime temperatures in the low- to mid-70s throughout the weekend, both in the immediate Washington area and at the Atlantic Ocean beaches from Delaware to North Carolina.

There's no chance of rain through Sunday, he says. But he warns that the long weekend might end on Memorial Day with a shower or two, although even that is only a 30-to-50-percent possibility.

Take note, however, that the ocean temperatures will do more than soothe your workaday worries. They will put a distinct chill on those who insist on inching more than a toe into the water.

The Delaware surf at such long-popular spots as Rehoboth Beach and Bethany Beach likley will only be in the mid-50s, Green says, while it will be in the upper 50s further south at Ocean City, Md., and in the low- to mid-60s at Virginia Beach and off the Outer Banks of North Carolina.

The other good news is that getting out of the Washington area, or around town for those who stay, may not prove all that difficult, unlike on some past summertime holidays. But there are a few cautionary notes to make.

Stay away, if you can, from 16th Street NW, between Emerson and Kennedy streets, where construction work has narrowed the roadway to a single lane in each direction. Ditto for the Benning Road NE viaduct, just west of Minnesota Avenue. And Pennsylvania Avenue NW, between 3rd and 10th streets, is still limited to traffic on the south side of the street. But otherwise, D.C. streets are clear of construction, highway officials say.

Maryland highway construction crews are taking a four-day holiday from work on the Woodrow Wilson Bridge over the Potomac River on the Capital Beltway's south side. There have been occasional massive traffic jams on and near the bridge in recent weeks, but state highway engineer Edward Meehan reports that all lanes on the bridge will be open from today through Monday.

Travelers heading to the Delaware and Maryland ocean beaches may encounter some heavy traffic crossing the Chesapeake Bay Bridge eastbound between 2 and 9 p.m. today and westbound from 1 to 10 p.m. on Monday.

But Sgt. William Hasenei of the Bay Bridge Police Department said he does not expect extensive backups, in part because the heaviest beach traffic occurs on the hottest weekends, usually in July and August. He said that if traffic becomes too congested, police can reverse two of the 14 bridge lanes so that the heaviest flow of traffic can use nine lanes instead of the normal seven.

Motorists will also be in for a pleasant surprise five miles east of the Bay Bridge when they approach the Kent Narrows drawbridge. The Coast Guard in years past has opened the drawbridge for boats to pass through every daytime hour on the hour, leaving beach-bound revelers steaming in a long line of overheating cars.

But no more, Maryland highway officials say.

Now, the drawbridge will only be opened at various intervals, depending on the day. Here's the schedule for this weekend: The bridge today will be raised on the hour from 6 a.m. until 3 p.m., if boats need passage, and again at 8 p.m. On Saturday, the bridge will be raised at 6 and 9 a.m., noon and on the hour from 3 to 8 p.m.. On both Sunday and Memorial Day, the raisings will be on the hour from 6 a.m. until 1 p.m. and again at 8 p.m. The length of the openings will likely range from 5 to 15 minutes.

"This new schedule should alleviate some of the congestion for motorists," highway spokesman Russell Ulrich said. Still, he advised motorists to try to avoid the drawbridge at all the lifting times, especially at the 8 o'clock opening tonight and at the one tomorrow at noon.

He said that further east on U.S. Rte. 50, some construction signs are posted, but that no work will be done over the weekend.

Delaware highway spokeswoman Michele Churchman said that motorists journeying to Rehoboth Beach will find that the weight limit on the Rte. 1 drawbridge just north of the city has been reduced from 12 tons to 3 tons, requiring recreational vehicle traffic to watch for signs for an alternate route into the beach area.

State police in Delaware, Maryland and Virginia say they will have extra troopers on the road throughout the weekend. In both Delaware and Maryland, state police are planning to post unannounced sobriety checkpoints on roads throughout the weekend, particularly between 8 p.m. and 3 a.m. Drinking drivers in Delaware will find that the mandatory fine for driving under the influence has doubled since last summer and now ranges from $200 to $1,000.

Virginia highway spokesman Al Coates said motorists might encounter some delays along a 55-mile stretch of Interstate Rte. 95 between Quantico and Ashland, north of Richmond, which is being widened from four to six lanes. Coates said that while no work is planned over the weekend, construction barriers have been placed on the existing roadway, narrowing one of the available lanes in each direction.

The restored area at Colonial Williamsburg is closed for the weekend for the ninth annual Summit of Industrial Nations, but state police said that Interstate Rte. 64 near Williamsburg will be open to traffic.

North Carolina highway officials report no construction projects on the roads leading to the Outer Banks.